1. Field of the Invention
This invention relates to an apparatus with the capability of detecting a two-dimensional code, and more particularly, to an apparatus with the capability of extracting copy control information embedded in a two-dimensional code, and a control method and a program of the same.
2. Description of the Related Art
In recent times, the issue of unauthorized copying of the document becomes increasingly serious along with the widespread use of copying machines. Techniques of addressing this issue include the techniques of restricting the copying of specific documents. In one of the techniques of restricting the copying of specific documents, a two-dimensional code including copy prohibition information is added to a document. Then, when a copying machine reads the document, it prohibits the document from being coped.
Two-dimensional codes added to documents include QR codes (Registered Trademark). Since this code is square in shape, the visibility of the code itself is high. If the code is added to the whole of image data, the readability of the original document is reduced. To avoid this, the two-dimensional code which is likely to reduce such readability is typically added to a part of the document, specifically, to one or more of the four corners of a sheet of the document.
When a copying machine having the copy prohibition function detects the QR code (Registered Trademark) added to a document, if the region intended to be detected spreads throughout an entire page of the document, it takes much time to perform image processing for code detection. To avoid this, in some cases, for detecting a code, the copying machine checks the four corners of the image read region for detection processing (Japanese Patent Laid-open No. 2008-263283). For example, to read an A4-size document 0101 shown in FIG. 1A, QR codes (Registered Trademark) are detected at the four points of the document, which are the upper left 0102, lower left 0103, upper right 0104 and lower right 0105. Then, if among them, the code including the copy prohibition information is added, the copy prohibition operation is performed.
However, the copy prohibition processing based on such a code may possibly be avoided and then a copy may be made. This event occurs when, for copying an A4-size document, a user specifies an A3 size for an image reading region. In such an event, as shown in FIG. 1B, an A4-size document 0107 shown by the thick line is read as an image of an A3-size region 0106 shown by the thin line. For information, the A3-size region 0106 encompasses the overall region of the A4-size document 0107. Because the image of the A3-size region 0106 is read, the regions on which the code detection processing is performed correspond to the four corners (0108-0111) of the A3-size image reading region, and the code detection processing is not performed on the upper right region 0112 and the lower right 0113 of the A4-size document 0107. As a result, there occurs a problem that even if the code including the copy prohibition information is added to the upper right corner or the lower right corner of the A4-size document, the copy prohibition operation is not performed to enable copying.